Newborns of heavy mothers at risk for breathing problems

NEW YORK (Reuters Health) - Babies of overweight and obese
mothers are more likely to have oxygen-deprivation problems at
birth, according to a new study.

The heavier a woman is, the greater the risks to her
newborn, researchers found.

"Maternal obesity is associated with a number of
complications during pregnancy and delivery, but the underlying
mechanism is not fully understood," said Dr. Marie Blomberg of
Linkoping University in Sweden. She was not involved in the new
study.

To learn more, researchers analyzed data from a medical
register of all live singleton, term births between 1992 and
2010 in Sweden, which included more than 1.7 million babies.

The register had information on women's height and weight
early in pregnancy, as well as babies' medical problems and
so-called Apgar scores.

The Apgar score assesses vitality using measures of heart
rate, breathing, muscle tone, skin color and activity on a scale
from zero to 10. There can be many reasons for a low Apgar
score, but the most common reason is lack of oxygen, lead author
Dr. Martina Persson told Reuters Health in an email.

Persson worked on the study at the Karolinska Institutet in
Stockholm.

Less than one in 1,000 babies had an Apgar score between
zero and 3 at five minutes after birth, and even fewer had that
low a score at 10 minutes after birth.

Compared to babies of normal-weight mothers, babies with
overweight mothers were 32 percent more likely to have an Apgar
score that low at 10 minutes.

Babies of obese mothers were 57 percent more likely to have
a low Apgar score, and those of severely obese mothers were 80
percent more likely.

A newborn's risk of seizures also increased with maternal
weight. For instance, babies of severely obese mothers were
twice as likely to have a seizure as those of mothers with a
healthy weight.

The increased risks were similar for meconium aspiration,
which happens when the baby releases stool in the womb and
inhales the stool-tainted amniotic fluid.

"Meconium release is a sign of fetal stress," Persson said.
"Meconium aspiration may give severe breathing problems in the
newborn and is associated with birth asphyxia and low Apgar
scores."

"Meconium aspiration and seizures could be serious in the
immediate newborn period although still the majority of these
children will be healthy," Blomberg told Reuters Health in an
email.

Researchers don't know why these risks, which all relate to
lack of oxygen, go up for babies of overweight and obese women,
Persson said.

Obesity in pregnant women has been associated with metabolic
changes and inflammation, which could affect the placenta and
fetal environment in a way that leads to low oxygen levels and
more fetal growth, she noted.

Also, larger babies, often born to larger mothers, may be
more likely to experience trauma during delivery, which could
result in lack of oxygen, she said.

"One must bear in mind that even though these conditions are
potentially very dangerous for the baby, the absolute risks for
the studied outcomes are low," Persson said.

Even with the most obese mothers, the risk of infants having
a low Apgar score at five minutes was still only 0.24 percent,
or less than three babies out of every 1,000.

In addition to encouraging prospective mothers to strive for
a healthy weight, doctors can closely monitor babies during
labor and delivery, which likely reduces the risk of lack of
oxygen at birth, she said.

"Enjoy your pregnancy!" Persson said. "Try to eat healthy
and be physically active. Seek support from your midwife in
order to change bad eating habits and try not to gain too much
weight during pregnancy."